Paper 28

Multi-stage yield and quality improvement of hemp fibres for clothing applications - prerequisite for revival of hemp cultivation

Fabrics consisting of natural or man-made fibres of cellulosic origin are widely used in clothing, for their comfort-related properties among others. Despite its huge ecological footprint, specifically high water and pesticide consumption during cultivation, cotton is still the most used natural fibre in the textile industry. Lately interest in hemp cultivation is becoming more prevalent in many industrialized countries as a consequence of its environmentally friendly cultivation, sustainable processing and versatile applications of the entire hemp plant. Hemp fibres are nowadays mainly used for the pulp and paper industry, building, technical textiles, animal bedding, pellets, etc. Lack of knowledge during cultivation, pre-processing and the spinning of long fibres, as well as inconsistent fibre quality are the main reasons that impede the use of hemp fibres for high-quality clothing applications.

The choice of the hemp variety, and sowing and harvesting conditions seem to be decisive during hemp cultivation, and the retting process is responsible for a great deal of fibre yield and quality. These approaches are investigated by the research project ‘Own grown hemp’ aiming at a revival of the hemp industry in Flanders, and which specifically investigates how the quality of hemp fibre can be controlled at several stages in the value chain. This paper presents selected results of the project relating to the relationship between fibre quality and yield, genotype and retting method. Five hemp cultivars (USO 31, Dacia Secuieni, Bialobrzeskie, Futura 75, Carmagnola Selezionata CS) and two types of retting (field or dew retting and enzymatic field retting with Texazym SER-7 conc.) are discussed.

In this study, genotype proved to be relevant for determining the fibre yield and quality of hemp. Although dry matter yields tended to be higher in the late flowering genotypes (Bialobrzeskie and CS) because they reached a bigger plant height at full flowering (237 cm and 279 cm respectively), bast fibre content was highest (38%) in the early flowering genotype (USO 31). The method of retting not only slightly affected the colour but also the fineness and strength of the hemp fibres and the differences were significant depending on cultivar. The results seem also to recommend enzymatic field retting as a better alternative to field retting in terms of fiber tenacity.